The normal transverse mounted bike carriers are limited to about 175kg, and that's without the problem of getting the beast onto a carrier. Even with a tag axle there's a lot of rear overhang. I think the OP is going to have to choose between a trailer of some sort or a lighter bike. Even if I could I wouldn't take my GS on my motorhome, it's way more bike than I need when I'm away on holiday.

. Just need an electric pushbike hanging off the back and Bobs yer auntie 
